This invention relates to improvements in molds for forming hollow articles, and more particularly to improvements in molds having means for severing a portion of the formed hollow article from the remainder thereof while the article is in the mold.
U.S. Pat. No. 3,869,237, issued Mar. 4, 1975 to E. W. Hellmer and J. P. Kinsley and assigned to the assignee of the present invention, discloses a mold for forming a hollow article having a body portion, an extension portion, and a transverse shoulder joining the body and extension portions. A first mold portion defines a cavity for forming the body portion and transverse shoulder, and a second mold portion defines a cavity extension for forming the extension portion of the article, the cavity extension communicating with the cavity. A pair of partible mold members cooperate to provide the first and second mold portions.
The second mold portion includes a cutter means for severing the extension portion of the formed article from the body portion at the transverse shoulder while the article is in the mold, the cutter means extending outwardly from the second mold portion to the first mold portion and defining a portion of the cavity extension. The second mold portion is axially movable in the direction of the first mold portion to bring the cutter means into cutting relation with the transverse shoulder.
The specification of the aforementioned patent explains that among other advantages in employing such an arrangement, the cutter means is accurately positioned with respect to the formed article, and the axial cutting operation, performed while the article is in the mold, obviates trimming and reaming operations conventionally performed after the hollow article has been removed from the mold.
In the prior arrangement, the extension portion of the formed article, being confined within the second mold portion, is constrained to move with it toward the first mold portion during the cutting operation. This tends to urge the transverse shoulder in the same direction as the cutter means, although movement of the shoulder is somewhat resisted by the body portion of the article, which remains confined within the first mold portion. However, a longer cutting stroke is required than would be the case if the extension portion, and thus the transverse shoulder, were to remain stationary relative to the body portion during the cutting operation.